1. Field of the Invention
The present invention relates generally to a splice closure apparatus for a cable or the like, and more specifically to a weather impervious splice closure apparatus for containing and providing ready access to a splice of a combination ground and fiber optic communications cable, commonly called an optical ground cable.
2. Description of the Related Art
Recent advances in communication technology have resulted in an ever increasing need for voice communications, video and data information transfer services, which capacity can most reliably and economically be provided by the use of fiber optic communications network paths. With the explosion of fiber optic cables being installed, there is an ever increasing need for additional physical paths for them.
The existing high tension electrical power distribution system in the United States provides an ideal vehicle for the placement of fiber optic cables. This is due to a number of factors, most notable of which are valuable property easements and rights of way which are already established. In addition, the high tension towers themselves, by serving as a stable, elevated platform for the fiber optic cables, act to provide a secure cable environment while simultaneously providing ready maintenance access to the fiber optic cables themselves. Most high tension electrical towers have ground cables attached to and extending between the topmost spars of each tower for protection from stray electrical discharges and as lightning arresters. Specialized multi-layer combination ground and fiber optic communications cables have been developed expressly for replacing these ground cables and typically include a continuous hollow metallic tube through which one or more fiber optic bundles are strung. This hollow tube is surrounded by a ground shield made up of a stranded aluminum wire layer, thus yielding a multi-layer coaxial cable typically called an optical ground cable.
Inevitably, such optical ground cables must be spliced, during initial installation to connect cable runs, and, after they are placed in operation, for maintenance or repair. Unlike conventional communication cables, however, a single fiber optic bundle can carry hundreds of thousands of simultaneous telephone conversations or data transmissions. Needless to say, a total interruption of such a bundle would be disastrous. Therefore, maintenance access must be provided to an existing optical ground cable splice or for implementing a new spice of a portion of a fiber optic cable without totally disrupting its continuity.
U.S. Pat. No. 5,007,701, ('701 patent) issued Apr. 16, 1991 to the present inventor, discloses a splice closure apparatus in which a rigid, cylindrical and weather impervious outer structure is open at both ends. A pair of end caps each include an elastomeric sealing material sandwiched between a pair of rigid plates. At least one of the end caps has openings for the passage of cables therethrough into the interior of the closure where an anchoring member is positioned to receive the cable ends and secure a splice. The elastomeric sealing material in each end cap is compressed against the sides of the outer cylinder by the plates on either side when a number of through bolts are tightened, thus forming a weather tight seal between each end cap and the cylinder wall. In addition, in each end cap with cable openings, the elastomeric material is simultaneously urged tightly against the cables, thus also forming a weather tight seal between the end cap and the cables.
While the '701 patent provides significant advantages over the prior art, it is not entirely suitable for splicing optical ground cables due to the multi-layer construction of such cables. In addition, as earlier mentioned, often in such cables, only a portion of an existing cable needs to be spliced, and the splice placed into a protective splice closure. This must be done without totally severing the cable and thus disrupting the extensive communication network it represents. In the '701 patent, as in other prior art splice closures, a continuous existing cable cannot be introduced into the closure without first totally severing the cable since the cable through passages are isolated in the end caps.
It is clear then that a need exists for a splice closure apparatus which is weather impervious and which can accommodate multi-layer optical ground cables. Such a closure apparatus must be capable of providing ready access to the interior thereof. In addition, the closure apparatus should accommodate the introduction of a continuous cable for a splicing operation without requiring the cable to be severed prior to introduction in the closure.